1 1 Know What You re Monitoring! Since not all of us are water chemists, here is a brief understanding of what your different tools measure Extech EC400 meters Salinity (SAL) Total Dissolved Solids (TDS) Conductivity (CON) Water Temperature ( C) Testing Strips 5- way water check: ph, Total Alkalinity, Total Hardness, Total Chlorine, Free Chlorine Nitrate/Nitrite strips Tools and Units Extech EC400 unit 5 way water check unit Nitrate/Nitrite unit Total Dissolved Solids (TDS) ppm or mg/l ph S.U. Nitrate ppm Conductivity µs Total Hardness ppm Nitrite ppm Salinity ppm Total Chlorine ppm Water Temperature C Free Chlorine ppm Total Alkalinity ppm Measurement Unit Definitions mg/l (milligrams per liter) Measures concentration of grams in a liter of water (or other liquid or gas) ppm (parts per million) Measures very dilute concentrations: a part of something in a larger total amount µs (micro siemens per cm.) Measures electric conductance S.U. (standard units) ph is measured on a scale of 1-14; SU reflects that scale s values.
2 2 Extech EC400 TOTAL DISSOLVED SOLIDS (TDS) Definition: TDS measures the combined amount of dissolved organic and inorganic substances in the water other than pure H20. Unit: ppm or mg/l Natural sources: leaves, plankton, weathering and dissolution of rocks and soils Man- made sources: Agricultural, residential runoff, leaching of soil contamination, point- source water pollution from industrial sites or sewage treatment plants, runoff from de- icing salts Most common chemicals: calcium, phosphorous, nitrates, sodium, potassium, chloride High levels are often caused by high amounts of potassium, chlorides and sodium. However, they may also be caused by the presence of toxic ions: lead, arsenic, cadmium, nitrate US EPA Levels for Drinking Water Drinking Water TDS Standards > 500 (mg/l) High levels can produce a laxative effect Yikes! TDS Standards A certain level of TDS ions are necessary for aquatic life. Fluctuations in TDS concentrations, however, can be harmful as TDS levels affect the flow of water into and out of an organism s cells. levels of TDS can degrade and diminish aquatic life. 1 A few cases have shown spawning and juvenile fish to be very sensitive to TDS levels. Ex: In San Francisco Bay- Delta, areas with 350 mg/l of TDS showed reduced levels of spawning Striped Bass; concentrations below 200 mg/l promoted healthier spawning. 2 Streams > 1500 mg/l Lake Erie > 200 mg/l Usually, freshwater aquatic ecosystems involving mixed fish fauna can tolerate TDS levels of 1000 mg/l. 1 Mitchell and Stapp, 1992 Field manual for water quality monitoring: An Environmental Education Program for Schools 2 Kaiser Engineers, Final Report to the State of California, San Francisco Bay- Delta Water Quality Control Program (1969)
3 CONDUCTIVITY 3 Definition: Conductivity measures the ability of an electrical current to pass through water. Levels of conductivity are affected by the presence of inorganic dissolved solids. Unit: µs/cm Natural sources: Geology of the area, water temperature, size of watershed Man- made sources: Agricultural, residential runoff, leaching of soil contamination, point- source water pollution from industrial or sewage treatment plants, runoff from de- icing salts Most common chemicals: chloride, nitrate, sulfate, and phosphate negative ions (anions), sodium, magnesium, calcium, iron, aluminum positive ions (cations). High levels of Conductivity may be caused by high water temperatures, presence of clay, metals Low levels of Conductivity may be caused by organic compounds such as oil (oil spills), phenol, alcohol, sugar, and presence of granite 3 Drinking Water Distilled water = µs Drinking water > 500 µs Historical Data Avg.: 641 µs Each stream tends to have a relatively constant range that can be used as a baseline; significant changes could indicate a discharge or other source of pollution has entered a stream. Streams > 500 µs Rivers > 1500 µs Historical Range µs Industrial Waters Up to 10,000 µs SALINITY 3 US EPA, Water Monitoring and Assessment, What is Conductivity and why is it important?
4 SALINITY Definition: The total of all non- carbonate salts dissolved in water; can often be detected by an increase in chloride. Unit: ppm 4 Natural sources: River streambeds with salt- containing minerals Man- made sources: Runoff from salted roads, impervious surface coverage/stormwater runoff, irrigation water returned to streams, chlorinated drinking water, water softener regeneration, fertilizers and pesticides Most common chemicals: calcium, sodium, chloride, and carbonate. Drinking Water This diagram shows salinity in parts per thousand (ppt). For parts per million (ppm), multiply by Example: Freshwater = between 0 and 500 ppm, Brine water =50,000 ppm > 250 ppm 250 ppm: harmful to freshwater life 1,000 ppm: lethal and sublethal effects on aquatic plants and invertebrates
5 5- way water check 5 ph 4,5 Definition: ph measures the acidity or alkalinity (base) of a solution. Unit: S.U. Natural sources Low ph values (acidic): Decomposing pine or fir needles; granite rock; snow melt, unpolluted rain; stormwater runoff that reaches stream before percolating through soil Higher ph values (basic): Calcium carbonate present in soil or rock act as buffers to acid; aquatic plant photosynthesis: highest levels in the late afternoon ph Scale: 0 to 14 Neutral water = 7 Acidic < 7 Basic > 7 * ph of 6 is 10x more acidic than a ph of 7 and 100x more acidic than ph of 8 Man- made sources Low ph values (acidic): Acid rain caused by pollution from industrial or large urban areas (sulfuric acid from coal, nitric acid from cars); point source pollution; mining: exposes rocks to rain water and produces acidic runoff. Low ph levels can make already present ammonia increasingly toxic. Heavy metals such as cadmium, lead, and chromium dissolve more easily in lower ph levels; many chemicals become more toxic when dissolved High ph values (basic): fertilizer and sewage runoff. High ph, phosphorous, and water temperature are breeding grounds for algae Drinking Water ph Range: S.U. ph Range: S.U. 4 US EPA, National Recommended Water Quality Criteria, 5 US EPA, Secondary Drinking Water Regulations: Guidance for Nuisance Chemicals,
6 Total Hardness Definition: Measure of mineral content in water. Unit: ppm Common Chemicals: Calcium: Calcite & Gypsum, Magnesium 6 Water hardness does not have an effect on human health but does cause problems in industrial settings with clogging. Healthy range: Calcium (40-80 ppm) and Magnesium (20-30 ppm) Total Chlorine Definition: Measure of both free and combined forms of chlorine. Unit: ppm Combined chlorine is free chlorine that has reacted with other substances in water and has therefore made the free chlorine less toxic. Free Chlorine Free Chlorine (chlorine gas dissolved in water) is toxic to fish and other aquatic organisms, even in small amounts. If water contains a lot of decaying materials, free chlorine can combine with them to form trihalomethanes (THMs). Some high concentrations of these are carcinogenic and persist in water for a long time. Total Alkalinity Total alkalinity is the amount of acid needed to bring a water sample to a ph of 4.2 S.U. At this level, all of the alkaline compounds are used up. Nitrate Nitrates are mainly used in fertilizers because they are highly soluble and biodegradable. Other sources include raw sewage and livestock feedlots. Nitrates refer to ammonium, sodium, potassium, and calcium salts. In freshwater, nitrate levels over 30 ppm can impact aquatic species by inhibiting growth, impairing immune systems, and causing stress. Nitrite Once consumed, Nitrates turn to Nitrites. Other sources include runoff from fertilizer use; leaching from septic tanks, sewage; and erosion of natural deposits. The Maximum Contaminant Level Goal for Nitrites is 1 ppm. An effective treatment to remove nitrites from drinking water is reverse osmosis.